thomasmueller commented on code in PR #2540:
URL: https://github.com/apache/jackrabbit-oak/pull/2540#discussion_r2379402723
##########
oak-core/src/main/java/org/apache/jackrabbit/oak/query/UnionQueryImpl.java:
##########
@@ -324,7 +324,21 @@ public Iterator<ResultRowImpl> getRows() {
rightIter = ((MeasuringIterator) rightRows).getDelegate();
}
if (orderBy == null) {
- it = IteratorUtils.chainedIterator(leftIter, rightIter);
+ boolean sortByScoreEnabled =
settings.isSortUnionQueryByScoreEnabled();
+ boolean leftHasScore = isScorePresent(left);
+ boolean rightHasScore = isScorePresent(right);
+
+ if (sortByScoreEnabled && leftHasScore && rightHasScore) {
+ // Both sides have scores => merge
+ Comparator<ResultRowImpl> scoreComparator =
createScoreBasedComparator();
+ it = IteratorUtils.mergeSorted(List.of(leftIter, rightIter),
scoreComparator);
+ } else if (sortByScoreEnabled && rightHasScore) {
+ // Only right has score => start with right
+ it = IteratorUtils.chainedIterator(rightIter, leftIter);
+ } else {
+ // Default old behavior, only left has score, or neither has
scores => start with left
+ it = IteratorUtils.chainedIterator(leftIter, rightIter);
+ }
Review Comment:
I usually start with the case where the feature is disabled, so that no new
code (that might have some bugs / forgotten edge cases) can cause issues;
something like this:
```suggestion
boolean sortByScoreEnabled =
settings.isSortUnionQueryByScoreEnabled();
if (!sortByScoreEnabled) {
it = IteratorUtils.chainedIterator(leftIter, rightIter);
} else {
boolean leftHasScore = isScorePresent(left);
boolean rightHasScore = isScorePresent(right);
if (leftHasScore && rightHasScore) {
// Both sides have scores => merge
Comparator<ResultRowImpl> scoreComparator =
createScoreBasedComparator();
it = IteratorUtils.mergeSorted(List.of(leftIter,
rightIter), scoreComparator);
} else if (rightHasScore) {
// Only right has score => start with right
it = IteratorUtils.chainedIterator(rightIter, leftIter);
} else {
// only left has score, or neither has scores => start
with left
it = IteratorUtils.chainedIterator(leftIter, rightIter);
}
}
```
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